ABSTRACT
A monocrystalline silicon cell needs absolutely pure semiconducting material to be produced. Monocrystalline rods are extracted from melted silicon and then sawed into thin plates in order to guarantee a level of e¢ciency that is considerably higher than that one characterizing polycrystalline cells. In this context, e¢ciency is given by the ratio between the electric power produced by the cell and the solar power incident on the cell area. Polycrystalline cells are produced by means of a more coste¢cient process: liquid silicon is poured into blocks that are subsequently sawed into plates. že lower e¢ciency of this type of solar cells is due to crystal defects emerging at the borders during solidiŸcation of the material, when crystal structures of varying sizes are formed. On average, in 2003, the thickness of wafers used for producing such cells was 0.32 mm, it decreased to 0.17 mm in 2008, while e¢ciency increased from 14% to 16% over the same period. By 2010, the aim is to reach 0.15 mm and 16.5% of wafer thickness and e¢ciency [8].
